Authenticating Data

When a wireless user attempts to acquire access to your wired network
infrastructure, there are two ways in which access can be obtained:
1. Open system—Any user in range of the access point can roam onto
the system (as long as the router is not set up to filter out the
unique MAC address of wireless workstations that are not supposed
to have access).
2. Encrypted system—All data is scrambled and access barriers are
put into place so that a hacker cannot eavesdrop on your data (Figure
4.2).

In an open system without encryption, a wireless workstation can join
your WLAN by using identity types of verification methods. The actual
access request in an open environment occurs when the wireless server
replies with the service set identifier (SSID) for the WLAN. This means
there isn’t any actual authentication taking place; the wireless workstation
simply roams onto the network.
In contrast, you can see the differences spelled out between an open
versus closed system:
Open System Closed System
Encryption Nothing RC4
Authentication No SSID SSID

Because of the unique SSID set for a company, many people believe
that nobody could actually roam onto a network without knowing what
unique identifier defined the network. In fact, it is possible for a wireless
user to leave the SSID as “NULL” or blank; then when he is in
range of the access point, the wireless workstation automatically finds
and logs into the network. This means that basic systems of authentication
are not sufficient to protect your network. This is why a combination
of encryption and authentication is important in implementing your
wireless security—but this still represents a small part of what needs to
be done to provide a truly secure WLAN. 73